Increased efficiency with mucochloric acid hardening by use of 4-substituted urazoles



United States Patent '0 INCREASED EFFICIENCY WITH MUCOCHLORIC ACIDHARDENING BY USE OF 4-SUBSTITUTED URAZOLES William W. Rees and WilliamH. Russell, Rochester, N.Y., assiguors to Eastman Kodak Company,Rochester, N.Y., a corporation of New Jersey N Drawing. Filed Dec. 21,1964, Ser. No. 420,196

6 Claims. (Cl. 96-109) This invention relates to photographic elements,more particularly photographic silver halide emulsions containingfog-inhibiting agents and hardeners.

For most photographic applications adequate levels of hardness for thegelatin-silver halide photographic emulsion must be maintained.Ordinarily, photographic emulsions on storage tend to lose sensitivityand become fogged, i.e., developable without exposure to light.Therefore, it is desirable in such emulsions to have present substanceswhich act as fog inhibitors and stabilizers therein. In the processingof photographic emulsions, it is important that the emulsion layermaintain satisfactory physical strength so as to resist physical andenvironmental degradation. Urazole has been considered a verysatisfactory additive to photographic emulsions to exert a stabilizingand fog-inhibiting effect thereon. However, urazole as an antifogganthas been restricted to use in conjunction with certain types of gelatinhardeners since it has the undesirable property of reacting withaldehydetype gelatin hardeners, resulting in a detrimental effect onhardening by the aldehyde-type hardener.

One object of our invention is to provide photographic emulsionscontaining both stabilizer (antifoggant) and aldehyde-type hardenerwhich do not detract from each others effectiveness in the emulsion.Another object of our invention is to provide photographicgelatin-silver halide photographic emulsions containing as the hardener,a halogen substituted aldehyde acid compound and, as the stabilizer, acompound of the urazole type therein. Other objects of our inventionwill appear herein.

We have found that by using as the aldehyde type gelatin hardener ahalogen substituted aldehyde acid and by using as the antifoggant orstabilizer a urazole substituted with an alkyl or aryl group or ahydrazide of maleic or phthalic acid both the stabilizing action and thehardening action of the respective compounds in the photographicemulsions are obtained with good effect.

The gelatin hardeners which have been found useful in our invention arethose which have been described and claimed in US. Patent No. 2,080,019of Frank L. White, particularly mucochloric acid or mucobromic acid. Asa stabilizer or antifoggant, compounds which have been found to beeffective in the presence of mucochloric or mucobromic acid aresubstituted urazoles having the formula:

wherein R is either H, alkyl or aryl, only one of the Rs being hydrogen.Also useful in this connection are the monoacyl or diacyl derivatives ofcompounds having this formula as for example the diacetyl derivative of4-phenyl urazole. Compounds in accordance with this structural formulawhich are especially useful in this connection are 4-phenyl urazole,l-phenyl urazole, 4-ethyl urazole, 4-naphthyl urazole and the like.Other compounds of this type which are useful in this connection aremaleic acid hydrazide and phthalic acid hydrazide.

Typical alkyls which can be used as substituents are methyl, ethyl,propyl, butyl, etc. Typical aryls or aralkyls 3,295,980 Patented Jan. 3,1967 used will be within the range of 0.l0.5%, based on the weight ofthe gelatin in the emulsion. The antifoggants specified exert anantifoggant eifect in most any concentration. However, ordinarily theantifoggant used in combination with the halogenated aldehyde acidcompound in accordance with our invention will be present in an amountof .55%, based on the weight of the gelatin in i the silver halideemulsion. Whereas when the urazole derivatives of our invention areutilized with other aldehyde hardeners there is ordinarily an effect onone by the other so as to interfere with their respective hardening(hardeners) or stabilizing (urazoles) actions, in the combination inaccordance with the invention the hardening eifectiveness and thestability effectiveness are maintained or in some cases increased whenused in photographic emulsions.

The following examples illustrate more specifically the invention: r

EXAMPLE 1 A coarse-grain gelatin-silver bromoiodide emulsion containing139 grams gelatin per silver mole such as adapted for X-ray material wasripened to optimum sensitivity by adding the desired sensitizing agentsand digesting. There was added thereto, as the hardener, 0.29 gram ofmucochloric acid per gram molecular weight of silver (or per 139 gramsof gelatin) in the emulsion plus addenda such as may be added in themaking of photographic emulsions. In one sample of the emulsion n0antifoggant was used. To another sample, urazole was added and to threeothers were added, respectively, 4-phenyl urazole, 4-ethyl urazole and4-naphthyl urazole. The emulsion samples were coated out onto cellulosetriacetate base and the film samples thus obtained were tested forpercent vertical swell of the'gelatin emulsion layers in an aqueous bathhaving a pH of 10 and in distilled water each in relation to the drylayers. The melting points of each of the samples was also determined.The results obtained with the various samples were as follows:

Table I Percent Vertical G'lAg Swell mole Addendum Distilled WaterBuffer p oiowo 0000 Ethyl urazole Naphthyl urazole" EXAMPLE 2 In asimilar procedure as in the preceding example several different aldehydetype hardeners were used, namely mucochloric acid, formaldehyde andsuccinaldehyde and the antifoggant used was 4-phenyl urazole at a levelof 2.0 grams per silver mole. The results obtained with and without theantifoggant both as to percent vertical swell in distilled water and asas to the melting points of the photographic emulsion layers were asfollows:

A coarse grain silver bromoiodide gelatin emulsion was chemicallysensitized. The emulsion contained 139 grams of gelatin per mole ofsilver halide. There was added thereto 0.29 gram of mucochloric acid permole of silver halide. The emulsion was divided into several portionsand l-phenyl urazole was added in theparts given. Each portion was thencoated onto polyethylene terephthalate film support. A sample of eachwas exposed on an intensity scale sensitometer and processed for 6minutes in Kodak Rapid X-ray Developer. The vertical swell, relativespeed and melting point were determined. The following results wereobtained:

l-Phenyl Urazole (g./rnole Relative Percent Melting of silver halide)Speed ,Vertical Point Swell F.)

EXAMPLE 4 Feature: Percent swell in developer Control-P029 grammucochloric acid/Ag mole 322 Control+0.75 gram urazole-|-O.29 grammucochloric acid/Ag mole 364 Control+0.75 gram maleic hydrazide-l-O.29

gram mucochloric acid/Ag mole 328 The invention has been described inconsiderable detail with particular reference to certain preferredembodiments thereof, but it will be understood that variations andmodifications can be effected within the spirit and scope of theinvention as described hereinabove, and as defined in the appendedclaims.

We claim:

- 1. A light sensitive gelatin-silver halide emulsion containing as ahardener therein a halogen substituted aldehyde acid compound selectedfrom the group consisting of mucochloric acid and mucobrornic acid andas an antifoggant therein a compound selected from the group consistingof the compounds having the following structural formula RN NH R beingselected from the group consisting of H, alkyl, aryl, and aralkyl onlyone R being hydrogen, the monoacetyl and diacetyl derivatives of thesecompounds, maleic acid hydrazide, and phthalic acid hydrazide.

2. A light sensitive gelatin-silver halide emulsion containing as ahardener therein mucochloric acid and as an antifoggant 4-phenylurazole.

3. A light sensitive gelatin-silver halide emulsion containing as ahardener therein mucochloric acid and as an antifoggant 4-ethy1 urazole.

4. A light sensitive gelatin-silver halide emulsion containing as ahardener therein mucochloric acid and as an antifoggant 4-naphthylurazole.

5. A light sensitive gelatin-silver halide emulsion containing as ahardener therein mucochloric acid and as an antifoggant l-phenylurazole.

6. A light sensitive gelatin-silver halide emulsion containing as ahardener therein mucochloric acid and as an antifoggant maleichydrazide.

No references cited.

NORMAN G. TORCHIN, Primary Examiner.

I. H. RAUBITSCHEK, Assistant Examiner.

1. A LIGHT SENSITIVE GELATIN-SILVER HALIDE EMULSION CONTAINING AS AHARDENER THEREIN A HALOGEN SUBSTITUTED ALDEHYDE ACID COMPOUND SELECTEDFROM THE GROUP CONSISTING OF MUCOCHLORIC ACID AND MUCOBROMIC ACID AND ASAN ANTIFOGGANT THEREIN A COMPOUND SELECTED FROM THE GROUP CONSISTING OFTHE COMPOUNDS HAVING THE FOLLOWING STRUCTURAL FORMULA